Ancient Baikal Plague Outbreaks Push Origins of Yersinia pestis Back to Mid-Holocene
Two waves of lethal Yersinia pestis outbreaks occurred among mid-Holocene hunter-gatherers near Lake Baikal around 5,500 years ago, with a 39% plague detection rate across four cemeteries. The Baikal strains are basal to known plague lineages and lack flea-transmission genes, implying rapid human-to-human spread (likely pneumonic) rather than flea-borne transmission. Outbreaks disproportionately affected children, clustered within tight radiocarbon date ranges, and kin groups show contemporaneous deaths, suggesting swift transmission within mobile communities. These findings push the plague’s origin earlier than Europe’s Neolithic cases and point to longstanding marmot/rodent reservoirs driving recurrent spillovers in Asia.